The "Wakajishi Sen" is a fictional tournament created by Hotta Yumi and Obata Takeshi for Hikaru no Go.
The format of this tournament is: Round 1 16 under 20-and under 5dan pros vs. 16 insei. Insei take Black.
It is not explained in the manga how the later rounds work out.
Known winners in the manga:
2001-2002 : Touya Akira
2000: Kurata
In the English translation it is known as "The Young Lions Tournament"'